The present invention generally relates to call handling in a communication network, and particularly relates to call handling for busy mobile stations where concurrent services are not supported.
Evolving wireless communication networks offer advanced packet data services along with legacy circuit-switched services. Packet data services include, for example, web browsing, streaming media, and email, while circuit-switched services include, for example, traditional low bit-rate voice and facsimile services usually associated with calls between subscribers on the Public Switched Telephone Network (PSTN) and subscribers operating in the wireless communication networks.
Several of the current wireless communication standards, such as the family of IS-2000 CDMA standards, include provisions for concurrent packet data and circuit-switched services. In a concurrent services environment where both the network and a particular mobile station support concurrent services, a user of the mobile station can send and receive voice calls while maintaining an active packet data connection with the network.
Despite such provisions in the standards, a great many existing wireless networks are not upgraded with concurrent services support, and a great many more existing mobile stations do not (and will not) support concurrent services. Lack of concurrent services support represents a challenge with regard to handling call termination and origination instances for busy mobile stations.
Broadly, mobile stations may be busy for a number of reasons. A mobile station may be busy in another voice call, busy in a packet data session, or busy in other non-voice calls that are not packet data calls in the strict sense. For example, a mobile station may be busy sending or receiving Position Location Determination (PLD) information, or busy sending or receiving Short Messaging Services (SMS) text or engaging in similar messaging activities. Where those services are allocated a dedicated traffic channel rather than an access channel, the mobile station is busy even though the mobile station user might not be aware of that condition.
Busy mobile stations pose potential service problems where concurrent service is not supported. In attempts to address the challenges presented in non-concurrent service scenarios, certain standards, such as the TIA-935 standard, define procedures for prioritizing circuit-switched calls over packet data calls. These procedures, referred to as Circuit-Switched Call Precedence Over CDMA Packet Data Session (CPOP), specify that if a (mobile station) user is engaged in a packet data call when an incoming voice call is received for that user, the network simply tears down the packet data connection and establishes a new connection for the incoming voice call. One additionally may refer to the IS-2001 Inter-Operability for cdma2000 Access Network Interfaces standard that details such a prioritization approach as it is being considered by the standardization bodies.
This brute force approach provides for delivery of the incoming voice call but includes the inelegant, at least from the users' perspective, step of simply dropping the data connection in favor of terminating the incoming voice call at the mobile station. Other types of communication networks, such as Wideband CDMA, may have similar call handling problems in non-concurrent service scenarios.